Nutrient analysis, metabolizable energy, and digestible amino acids of soybean meals of different origins for broilers V. Ravindran,*1 M. R. Abdollahi,* and S. M. Bootwalla†2 *Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand; and †United States Soybean Export Council, 541 Orchard Road, #11-03 Liat Towers, Singapore 238881 tent was markedly high (928 mg/kg) in SBM from IND compared with those from other origins (103–134 mg/ kg). Major origin-related differences (P < 0.0001) were observed in the AME of SBM. The average AME content of US, ARG, BRA, and IND samples was 2,375, 2,227, 2,317, and 2,000 kcal/kg (as-fed basis), respectively. Total AA contents of US, ARG, BRA, and IND samples were similar (P > 0.05) for 9 of the 17 amino acids. Major differences (P < 0.05 to P < 0.001) due to origin were determined for the digestibility of all AA. The IND samples had the lowest (P < 0.05) digestibility and no differences (P > 0.05) between samples from other 3 origins. However, the digestible CP content of US SBM was higher (P < 0.05) than those of ARG and IND, but similar (P > 0.05) to that from BRA. The digestible CP contents of SBM from the US, ARG, BRA, and IND were 40.0, 38.6, 39.8, and 36.7%, respectively. Digestible contents of indispensable AA, in general, followed the same trend as that of digestible CP. In conclusion, the present evaluation showed that major differences in nutritive value do exist between SBM from different origins in terms of nutrient contents, AME, and digestible AA. Overall, SBM originating from the US had better nutritive value compared with those from ARG and IND, on the basis of AME and contents of digestible CP and digestible AA.

Key words: amino acid digestibility, apparent metabolizable energy, broiler, soybean meal 2014 Poultry Science 93:2567–2577 http://dx.doi.org/10.3382/ps.2014-04068

INTRODUCTION Soybean meal (SBM) is by far the most commonly used source of protein in poultry diets worldwide. Its universal acceptability, compared with other oilseed meals, is due to favorable attributes such as relatively ©2014 Poultry Science Association Inc. Received March 30, 2014. Accepted June 30, 2014. 1 Corresponding author: [email protected] 2 Present address: DSM Nutritional Products, 2 Havelock Road #04-01, Singapore 059763.

high CP content, an excellent amino acid (AA) profile that complements cereals, and high AA digestibility. In a typical corn-soybean meal broiler diet, SBM contributes up to 70% of dietary CP. Thus, ensuring the quantity and quality of protein in SBM is of prime interest. The CP content of SBM is influenced by several factors, including cultivar, agronomic and soil conditions, climate, the extent of dehulling, and processing conditions. The CP content is routinely monitored by the feed industry and used to make adjustments in the nutrient matrix in feed formulations. The digestibility of CP by the animal is also equally important, and this is

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ABSTRACT Nutrient composition, ileal amino acid (AA) digestibility, and AME of 55 soybean meal (SBM) samples from the United States (US; n = 16), Argentina (ARG; n = 16), Brazil (BRA; n = 10), and India (IND; n = 13), collected from commercial mills in Southeast Asia, were compared using laboratory analyses and animal studies. There were significant (P < 0.05 to 0.001) differences due to origin in CP, fat, ash, fiber, and nonstarch polysaccharide (NSP) contents of SBM. The average CP content of US, ARG, BRA, and IND samples was determined to be 47.3, 46.9, 48.2, and 46.4% (as-fed basis), respectively. Compared with SBM from other origins, crude fiber and NSP contents were lower (P < 0.05) and sucrose content was higher (P < 0.05) in the US samples. The IND samples had the highest (P < 0.05) contents of fiber, ash, and NSP, and lowest (P < 0.05) contents of fat and sucrose. Differences (P < 0.0001) were observed among origins for in vitro protein quality measures (urease index, KOH protein solubility, and trypsin inhibitor activity). Significant (P < 0.001) effects due to origin were observed for all minerals. Soybean meal from the US and IND had higher (P < 0.05) calcium contents (0.45%) compared with those from ARG and BRA (0.28–0.31%). Phosphorus and potassium contents were lowest (P < 0.05) in SBM from IND, and no differences (P > 0.05) were observed in SBM from other origins. Iron con-

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MATERIALS AND METHODS A total of 55 SBM samples, imported as meals from respective origins, were collected during 2010 to 2012 from major commercial feed mills in South East Asia (Indonesia, Thailand, the Philippines, and Vietnam). The collection times corresponded to the harvest and processing periods in their countries of origin. The nutritional evaluation of samples was carried out in

3 phases, namely, (i) laboratory evaluation, (ii) AME assay, and (iii) ileal digestible AA assay. The experimental procedures for animal trials were approved by the Massey University Animal Ethics Committee and complied with the New Zealand Code of Practice for the Care and Use of Animals for Scientific Purposes.

Laboratory Evaluation Representative samples were obtained, ground to pass through a 0.5-mm screen and used for the analysis of DM, CP, crude fat, neutral detergent fiber (NDF), ash, NSP, sucrose, AA, urease test, potassium hydroxide (KOH) protein solubility, and TI activity. All analyses were performed in duplicate.

AME The AME of SBM was determined by the difference method. In this method, a corn-soy basal diet was formulated (Table 1), and the test diets, each containing different SBM samples, were developed by replacing (wt/wt) 30% of the basal diet with SBM. One-day-old male broilers (Ross 308), obtained from a commercial hatchery, were raised in floor pens and fed a commercial broiler starter diet (23% CP) until d 21. Feed and water were available at all times. The temperature was maintained at 32°C during the first week and gradually decreased to approximately 23°C by the end of the third week. Ventilation was controlled by a central ceiling extraction fan and wall inlet ducts. On d 21, birds of uniform BW were selected and randomly assigned to experimental cages (6 birds per cage) and 4 replicate cages were randomly assigned to each of the assay diets. The AME assay was conducted by the classical total excreta collection method. The diets, in mash form, were fed for 8 d, with the first 4 d serving as an adaptation period. During the last 4 d, feed intake was monitored, and the excreta were collected daily, weighed, and pooled within a cage. Pooled excreta were mixed

Table 1. Percentage composition of the basal diet used in the AME assay Ingredient Corn Soybean meal Soybean oil Dicalcium phosphate Limestone Sodium chloride Sodium bicarbonate Vitamin-trace mineral premix1

% 59.00 35.52 1.78 2.17 0.78 0.20 0.23 0.32

1Provided per kilogram of diet: Co, 0.3 mg; Cu, 5 mg; Fe, 25 mg; I, 1 mg; Mn, 125 mg; Zn, 60 mg; choline chloride, 638 mg; trans-retinol, 3.33 mg; cholecalciferol, 60 µg; dl-α-tocopheryl acetate, 60 mg; menadione, 4 mg; thiamine, 3.0 mg; riboflavin, 12 mg; niacin, 35 mg; calcium pantothenate, 12.8 mg; pyridoxine, 10 mg; cyanocobalalamin, 0.017 mg; folic acid 5.2 mg; biotin, 0.2 mg; antioxidant, 100 mg; molybdenum, 0.5 mg; selenium, 200 µg.

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influenced largely by the adequacy of heat-processing to destroy or reduce the level of antinutritional factors, especially trypsin inhibitors (TI). Both under- and overprocessing are detrimental to the effective use of SBM and are monitored by the in vitro laboratory tests such as urease test and protein solubility in potassium hydroxide. The United States (US), Brazil (BRA), and Argentina (ARG) are the dominant suppliers in the global SBM market. Soybean meal is also exported from India (IND), but exports fluctuate depending on domestic consumption of SBM. Variations of SBM from different origins in terms of CP, proximate analysis, and in vitro protein quality measurements have been highlighted in several publications (Thakur and Hurburgh, 2007; de Coca-Sinova et al., 2008; Frikha et al., 2012). Although the CP and nutrient composition data are useful in identifying differences between SBM samples, they are not directly related to animal growth. Metabolizable energy and AA digestibility are parameters that have a large effect on animal performance and consequently on profitability. It is essential, therefore, for nutritionists to ensure that the AME and digestible AA contents are considered in the selection of SBM to meet the desired specifications. Published data on AA digestibility of SBM from different origins, however, are limited. de Coca-Sinova et al. (2008) reported the ileal digestibility of AA and energy for broilers of 4 BRA and 2 US SBM samples. In the study of Frikha et al. (2012), the AA digestibility of 22 samples from the US (n = 8), BRA (n = 7), and ARG (n = 7) were reported. Despite the relevance of AME of SBM in feed formulations, published data comparing the AME of SBM across different origins are scant. It is important that large number of samples be assayed and the CV of nutritional parameters be reported for the development of an accurate formulation matrix for a feedstuff. The objective of this project was to assess if nutritionally relevant variation exists among SBM samples of different origins by comparing the chemical composition, AME and ileal AA digestibility of 55 SBM samples originating from US (n = 16), ARG (n = 16), BRA (n = 10), and IND (n = 13). The overall aim was to fully characterize the SBM samples in terms of proximate analysis, sucrose, nonstarch polysaccharides (NSP), protein quality measurements (urease index, protein solubility, and TI activity), mineral contents, total AA, AME, and standardized ileal digestibility (SID) of AA.

EVALUATION OF SOYBEAN MEAL OF DIFFERENT ORIGINS Table 2. Percentage composition of the assay diet used in the ileal amino acid digestibility assay Ingredient Soybean meal Dextrose Soybean oil Sodium chloride Sodium bicarbonate Dicalcium phosphate Limestone Vitamin-trace mineral premix1 Titanium dioxide 1See

% 41.60 52.48 2.00 0.20 0.20 1.90 1.00 0.32 0.30

Table 1 for provision per kilogram of diet.

Ileal AA Digestibility Assay Assay diets, based on dextrose and SBM as the only source of CP, were formulated to supply around 18% CP in the diet (Table 2). All diets contained titanium dioxide as an indigestible marker. After a 4-h fasting, birds used in the AME assay were redistributed to cages and each diet was offered ad libitum to 4 cages (6 birds per cage) from 29 to 34 d of age. On d 34 posthatch, all birds were euthanized by intracardial injection of sodium pentobarbitone solution (1 mL per 2 kg of live weight), and the contents of the lower half of the ileum were collected by gently flushing with distilled water into plastic containers. Digesta samples were pooled within a cage. The ileum was defined as the portion of the small intestine extending from vitelline diverticulum to a point 40 mm proximal to the ileo-cecal junction. The digesta were frozen at −20°C in airtight containers immediately after collection and subsequently freeze-dried. The digesta samples, as well as samples of ingredients and diets, were then ground to pass through 0.5-mm sieve and stored in airtight plastic containers. The diet and digesta samples were then analyzed for DM, titanium dioxide, and AA, whereas ingredient samples were analyzed for DM and AA.

Endogenous AA Losses Basal endogenous AA flow was determined in a cohort assay by offering a protein-free diet to 6 cages of 6 birds each from 29 to 34 d of age, as described by Ravindran et al. (2009).

Chemical Analysis The DM, CP, crude fat, NDF, and ash contents were determined using standard procedures (AOAC Interna-

tional, 2005). Nitrogen content was determined by the combustion method using a CNS-2000 carbon, nitrogen and sulfur analyzer (Leco Corporation, St. Joseph, MI). The CP content was calculated as N × 6.25. To determine the sucrose content, the samples were first treated with hydroxylamine hydrochloride and the resulting oximes are converted to the trimethylsilyl derivatives by the addition of hexamethyldisilazane and trifluoroacetic acid. The volatile derivatives were analyzed by gas liquid chromatography with a flame ionisation detector. Quantitation is by multipoint internal calibration. Total, soluble, and insoluble NSP were determined using an assay kit (Megazyme International Ireland Ltd., Wicklow, Ireland) based on thermostable α-amylase, protease, and amyloglucosidase (Englyst et al., 1994). Urease activity was determined as urease index, which is based on change in pH (Association of Official Analytical Chemists, 1980). Protein solubility in KOH was determined using the procedures of Araba and Dale (1990). Trypsin inhibitor activity, defined as the number of trypsin inhibitor units (TIU) per milligram of sample, was determined using the procedures of Kakade et al. (1974). For mineral analysis, the samples were wet acid digested with nitric and perchloric acid mixture, and concentrations of P, K, Ca, Mg, Na, and Fe were determined by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) using a Thermo Jarrell Ash IRIS instrument (Thermo Jarrell Ash Corporation, Franklin, MA). The concentrations of Cu, Mn, and Zn were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) using a Perkin Elmer Elan 6000 instrument (Melbourne, Victoria, Australia). Amino acids were determined as described by Ravindran et al. (2009). Briefly, the samples were hydrolyzed with 6 N HCl (containing phenol) for 24 h at 110 ± 2°C in glass tubes sealed under vacuum. The AA were detected on a Waters ion-exchange HPLC system, and the chromatograms were integrated using dedicated software (version 3.05.01, Millennium, Waters, Millipore, Milford, MA) with the AA identified and quantified using a standard AA mixture (product no. A2908, Sigma, St. Louis, MO). The HPLC system consisted of an ion-exchange column, two 510 pumps, Waters 715 ultra WISP sample processor, a column heater, a postcolumn reaction coil heater, a ninhydrin pump, and a dual wavelength detector. Amino acids were eluted by a gradient of pH 3.3 sodium citrate eluent to pH 9.8 sodium borate eluent at a flow rate of 0.4 mL/min and a column temperature of 60°C. Cysteine and methionine were analyzed as cysteic acid and methionine sulfone, respectively, by oxidation with performic acid for 16 h at 0°C and neutralization with hydrobromic acid before hydrolysis. Gross energy was determined using an adiabatic bomb calorimeter (Gallenkamp Autobomb, London, UK) standardized with benzoic acid. Titanium was determined using a colorimetric assay (Short et al., 1996).

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well, and representative samples were obtained and freeze-dried. Dried excreta samples were ground to pass through a 0.5-mm sieve and stored in airtight plastic containers at −4°C for laboratory analyses. The DM, gross energy, and N of the diet and excreta samples were determined.

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Calculations

Statistical Analysis

The AME of SBM was calculated using the following formulas:

Data were analyzed statistically by ANOVA using the GLM Procedure (SAS Institute Inc., 2004). Differences were considered significant at P < 0.05 and significant differences between means were separated by the least significant difference test. Correlations of measurements of interest with CP digestibility and AME were also determined.

AME diet (kcal/kg) = (feed intake × GE ) − (excreta output × GE diet excreta ) ; feed intake AMESBM (kcal/kg) =

AME of SBM diet − (AME basal diet × 0.70) . 0.30





AA digestibility =

(AA/Ti)d − (AA/Ti)i (AA/Ti)d

×100,

where (AA/Ti)d = ratio of AA to titanium in diet, and (AA/Ti)i = ratio of AA to titanium in ileal digesta. Apparent digestibility data were converted to SID values, using basal endogenous AA values from birds fed the protein-free diet method. SID (%) = AID (%)+

basal EAA (g/kg of DMI) ×100, ingredient AA (g/kgg of DM)

where AID = % apparent ileal digestibility of the AA, basal EAA = basal endogenous of the AA, and ingredient AA = concentration of the AA in the ingredient.

Proximate Analysis The data for proximate analysis are summarized in Table 3. There were significant (P < 0.01) differences between different origins for CP. Crude protein contents were higher (P < 0.05) in SBM from BRA and lowest (P < 0.05) in those from IND, whereas CP contents in the US and ARG SBM samples were intermediate. The variation, measured by CV, was lowest for US samples (0.9%) and highest for the BRA samples (3.4%). Significant (P < 0.001) differences were also observed in the contents of crude fat, ash, crude fiber, and NDF. The ash, crude fiber, and NDF contents were higher (P < 0.05) and that of crude fat was lower (P < 0.05) in the IND SBM than those from other origins (Table 3).

Carbohydrate Composition Carbohydrate analyses, presented in Table 3, include data for sucrose and insoluble, soluble, and total NSP. The sucrose content in SBM samples from the US was higher (P < 0.05) and that in IND samples was lower (P < 0.05) than those from other origins (Table 3). The

Table 3. Proximate analysis and carbohydrate composition (%; mean ± SD) of soybean meals from different origins, as-received basis1 Item DM CP Crude fat Crude fiber Ash NDF Sucrose Insoluble NSP Soluble NSP Total NSP a–cWithin

United States (n = 16)

Argentina (n = 16)

Brazil (n = 10)

India (n = 13)

Pooled SEM

P-value

89.2 ± 0.71 (88.0–90.6) 47.3 ± 0.44b (46.4–48.1) 1.63 ± 0.46b (1.31–3.35) 3.63 ± 0.41c (2.64–4.34) 6.43 ± 0.24b (5.84–6.71) 7.66 ± 0.88b (6.53–9.44) 8.29 ± 1.01a (6.79–9.84) 15.9 ± 1.26c (13.0–17.7) 1.66 ± 0.46ab (0.93–2.60) 17.6 ± 1.15b (15.4–19.3)

89.2 ± 0.69 (87.8–90.2) 46.9 ± 0.90bc (44.6–47.9) 1.86 ± 0.33ab (1.27–2.63) 3.67 ± 0.39c (2.96–4.54) 6.31 ± 0.27b (5.90–6.75) 8.35 ± 1.27b (6.60–10.9) 7.51 ± 0.96b (5.80–9.22) 16.8 ± 1.13b (14.6–18.7) 1.43 ± 0.36b (0.90–2.27) 18.3 ± 1.33b (15.8–20.4)

89.0 ± 1.03 (87.8–90.8) 48.2 ± 1.65a (45.4–49.9) 2.05 ± 0.59a (0.95–3.19) 4.05 ± 0.44b (3.56–4.94) 6.26 ± 0.51b (5.80–7.22) 8.53 ± 1.48b (6.10–11.1) 6.30 ± 0.94c (5.30–8.05) 16.9 ± 1.28b (13.9–18.3) 1.43 ± 0.26b (0.92–1.83) 18.3 ± 1.47b (15.0–20.1)

88.9 ± 0.62 (87.7–90.1) 46.4 ± 1.03c (44.1–48.5) 1.09 ± 0.23c (0.60–1.61) 6.08 ± 0.50a (5.10–6.90) 7.95 ± 0.82a (6.60–8.93) 12.8 ± 1.47a (10.0–14.9) 5.42 ± 0.74d (4.20–6.53) 18.7 ± 0.71a (17.4–20.3) 1.87 ± 0.34a (1.07–2.50) 20.6 ± 0.83a (19.2–22.3)

0.21

NS

0.28

**

0.115

***

0.121

***

0.138

***

0.353

***

0.259

***

0.31

***

0.104

*

0.34

***

a row, means without a common letter are significantly different (P < 0.05). in parentheses refer to ranges determined. NDF = neutral detergent fiber; NSP = nonstarch polysaccharide. *P < 0.05; **P < 0.01; ***P < 0.001. 1Values

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Apparent ileal AA digestibility (%) was calculated from the dietary ratio of AA to titanium relative to the corresponding ratio in the ileal digesta.

RESULTS

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EVALUATION OF SOYBEAN MEAL OF DIFFERENT ORIGINS Table 4. In vitro protein quality indicators of soybean meals from different origins, as-received basis1 United States (n = 16)

Item

0.06a

Urease index

0.081 ± (0.00–0.18) 77.2 ± 3.52a (67.8–82.4) 2.45 ± 0.30a (2.02–2.96)

KOH protein solubility Trypsin inhibitor activity (TIU/mg)

Argentina (n = 16)

Brazil (n = 10)

0.008b

0.01b

0.007 ± (0.00–0.02) 69.7 ± 2.71c (64.9–74.2) 1.98 ± 0.24b (1.66–2.57)

0.009 ± (0.00–0.03) 72.5 ± 3.17bc (65.2–77.2) 2.32 ± 0.32a (2.05–3.12)

India (n = 13) 0.042b

0.031 ± (0.00–0.16) 74.3 ± 5.01b (63.1–81.4) 2.37 ± 0.31a (1.91–3.03)

Pooled SEM

P-value

0.0114

***

1.02

***

0.081

***

a–cWithin

a row, means without a common letter are significantly different (P < 0.05). in parentheses refer to ranges determined. TIU = trypsin inhibitor units. ***P < 0.001. 1Values

Protein Quality Measures Though there were significant (P < 0.001) differences in the urease index of SBM from different origins, all values were low (Table 4). The KOH protein solubility of SBM samples of US origin was higher (P < 0.05) than those from other origins. The solubility of SBM samples from ARG was lower (P < 0.05) compared with those from the US and IND. Trypsin inhibitor activity was lower (P < 0.05) in ARG samples compared with those from other origins.

Mineral Composition Significant (P < 0.001) effects due to origin were observed for all minerals (Table 5). The US and IND SBM had higher (P < 0.05) Ca contents (0.45%) compared

with those from ARG (0.31%) and BRA (0.28%). Phosphorus contents were lowest (P < 0.05) in SBM of IND origin, and no differences (P > 0.05) were observed between SBM from other origins. Potassium contents were high in SBM from all origins, with average values ranging from 2.07 to 2.40%. Magnesium contents were higher (P < 0.05) in SBM from BRA and IND origins compared with those from the US and ARG. Although significant (P < 0.001) differences were observed for Na, the contents in all samples were low (0.01–0.02%). Among the micro minerals, Fe content was 8- to 9-fold higher (P < 0.05) in SBM from IND origin than those from US, ARG, and BRA. Copper and Mn contents were also higher in IND samples. The BRA SBM samples were determined to contain lower contents of Cu and Mn. The Zn content was higher in BRA and IND SBM compared with those from the US and ARG.

AME The AME content was higher (P < 0.05) in SBM from the US compared with that from ARG and IND (Table 6). There was no difference (P > 0.05) between the AME content of samples from the US and BRA. The IND SBM was determined to have the lowest (P

Table 5. Mineral contents (mean ± SD) of soybean meals from different origins, as received basis1 Item Calcium, g/100 g Phosphorus, g/100 g Magnesium, g/100 g Potassium, g/100 g Sodium, g/100 g Iron, mg/kg Copper, mg/kg Manganese, mg/kg Zinc, mg/kg a–cWithin

United States (n = 16) 0.10a

0.45 ± (0.27–0.63) 0.69 ± 0.05a (0.61–0.78) 0.31 ± 0.02b (0.29–0.36) 2.29 ± 0.14b (2.10–2.61) 0.006 ± 0.002b (0.004–0.01) 103 ± 17.3b (73.0–155) 14.5 ± 1.03b (13.2–16.6) 44.4 ± 5.29c (36.0–54.5) 50.1 ± 3.57b (43.0–55.0)

Argentina (n = 16) 0.02b

0.31 ± (0.28–0.36) 0.71 ± 0.04a (0.63–0.81) 0.32 ± 0.02b (0.30–0.36) 2.40 ± 0.11a (2.30–2.61) 0.011 ± 0.011ab (0.004–0.03) 118 ± 49.7b (83.0–280) 15.3 ± 0.82b (14.0–17.3) 52.2 ± 3.91b (48.0–63.0) 48.7 ± 2.17b (46.0–53.0)

Brazil (n = 10) 0.06b

0.28 ± (0.25–0.40) 0.69 ± 0.05a (0.64–0.78) 0.36 ± 0.04a (0.30–0.43) 2.31 ± 0.15ab (2.20–2.61) 0.018 ± 0.020a (0.004–0.05) 134 ± 31.0b (94.0–190) 12.1 ± 1.68c (10.0–15.6) 34.8 ± 3.68d (29.0–43.0) 54.5 ± 4.43a (49.0–62.0)

a row, means without a common letter are significantly different (P < 0.05). in parentheses refer to ranges determined. *P < 0.05; ***P < 0.001. 1Values

India (n = 13) 0.04a

0.46 ± (0.38–0.56) 0.57 ± 0.04b (0.50–0.63) 0.38 ± 0.03a (0.32–0.42) 2.07 ± 0.09c (1.96–2.28) 0.007 ± 0.002b (0.004–0.01) 928 ± 276a (563–1630) 16.8 ± 1.28a (15.0–18.8) 71.6 ± 12.4a (52.0–95.0) 54.8 ± 4.59a (47.0–62.0)

Pooled SEM

P-value

0.018

***

0.013

***

0.008

***

0.035

***

0.0026

*

38.4

***

0.33

***

2.00

***

1.03

***

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sucrose content of SBM from US, ARG, BRA, and IND was 8.3, 7.5, 6.3, and 5.4%, respectively. Insoluble NSP was lowest (P < 0.05) in SBM from the US (15.9%) and highest (P < 0.05) in samples from IND (18.7%). The soluble and total NSP contents were higher (P < 0.05) in SBM from IND compared with US, ARG, and BRA samples.

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Table 6. Apparent metabolizable energy (mean ± SD) for broilers of soybean meals from different origins, kcal/kg, as-received basis1 Item United States (n = 16) Argentina (n = 16) Brazil (n = 10) India (n = 13) Pooled SEM P-value

AME 2,375 2,227 2,317 2,000

± ± ± ±

114a (2,130–2,541) 148b (1,796–2,417) 165ab (2,003–2,531) 191c (1,567–2,299) 43 ***

a–cWithin a column, means without a common letter are significantly different (P < 0.05). 1Values in parentheses refer to ranges determined. ***P < 0.001.

Total AA Content Despite significant (P < 0.01) differences in the CP content of SBM from different origins, only 8 of the 17

AA Digestibility and Digestible AA Content The SID of CP was higher (P < 0.05) in SBM from the US, ARG, and BRA compared with those from IND (Table 9). No differences in CP digestibility existed between the US, ARG, and BRA samples. The SID

Table 7. Total amino acid contents (%, mean ± SD) of soybean meals from different origins, as-received basis1 Item Indispensable amino acid  Arginine  Histidine  Isoleucine  Leucine  Lysine  Methionine  Phenylalanine  Threonine  Valine Dispensable amino acid  Alanine   Aspartic acid  Cysteine  Glycine   Glutamic acid  Proline  Serine  Tyrosine a–cWithin

USA (n = 16)

Argentina (n = 16)

Brazil (n = 10)

India (n = 13)

Pooled SEM

P-value

3.56 ± 0.14 (3.36–3.84) 1.34 ± 0.04 (1.25–1.40) 2.22 ± 0.10 (2.07–2.43) 3.62 ± 0.11ab (3.43–3.91) 2.88 ± 0.20 (2.59–3.18) 0.72 ± 0.02a (0.68–0.75) 2.43 ± 0.08b (2.29–2.64) 1.86 ± 0.04a (1.79–1.95) 2.47 ± 0.11 (2.28–2.71)

3.45 ± 0.13 (3.21–3.69) 1.31 ± 0.06 (1.23–1.42) 2.19 ± 0.09 (2.07–2.42) 3.53 ± 0.14bc (3.28–3.87) 2.84 ± 0.19 (2.44–3.16) 0.68 ± 0.04bc (0.59–0.73) 2.45 ± 0.09b (2.32–2.60) 1.83 ± 0.08a (1.69–2.01) 2.41 ± 0.15 (2.17–2.71)

3.50 ± 0.16 (3.27–3.80) 1.35 ± 0.10 (1.14–1.50) 2.27 ± 0.15 (2.08–2.54) 3.73 ± 0.18a (3.49–4.08) 2.79 ± 0.25 (2.30–3.21) 0.69 ± 0.07ab (0.57–0.82) 2.61 ± 0.13a (2.34–2.81) 1.86 ± 0.09a (1.72–2.01) 2.45 ± 0.23 (2.08–2.81)

3.45 ± 0.15 (3.17–3.69) 1.32 ± 0.07 (1.20–1.47) 2.17 ± 0.11 (1.90–2.35) 3.48 ± 0.18c (3.18–3.73) 2.68 ± 0.21 (2.24–2.99) 0.66 ± 0.02c (0.61–0.69) 2.41 ± 0.10b (2.17–2.54) 1.75 ± 0.07b (1.63–1.85) 2.33 ± 0.19 (2.03–2.63)

0.040

NS

0.019

NS

0.030

NS

0.042

**

0.059

NS

0.011

**

0.027

***

0.020

***

0.046

NS

1.94 ± 0.08b (1.80–2.09) 5.47 ± 0.15b (5.15–5.85) 0.75 ± 0.03a (0.70–0.81) 1.90 ± 0.07 (1.80–2.03) 8.42 ± 0.36 (7.68–9.17) 2.45 ± 0.16 (2.15–2.71) 2.19 ± 0.08 (2.08–2.39) 1.73 ± 0.08ab (1.64–1.92)

1.95 ± 0.07b (1.86–2.13) 5.42 ± 0.19b (5.10–5.78) 0.71 ± 0.02b (0.67–0.75) 1.90 ± 0.09 (1.73–2.02) 8.34 ± 0.27 (7.99–9.04) 2.41 ± 0.21 (1.95–2.78) 2.17 ± 0.09 (1.96–2.30) 1.72 ± 0.09ab (1.49–1.86)

2.04 ± 0.08a (1.94–2.19) 5.68 ± 0.24a (5.26–6.05) 0.73 ± 0.04ab (0.66–0.80) 1.96 ± 0.07 (1.85–2.04) 8.63 ± 0.52 (7.79–9.48) 2.52 ± 0.22 (2.15–2.80) 2.24 ± 0.11 (2.06–2.43) 1.78 ± 0.11a (1.55–1.88)

1.87 ± 0.07c (1.75–1.99) 5.44 ± 0.21b (5.01–5.85) 0.67 ± 0.03c (0.63–0.74) 1.89 ± 0.10 (1.71–2.09) 8.44 ± 0.31 (7.66–8.86) 2.41 ± 0.18 (2.04–2.67) 2.16 ± 0.14 (1.98–2.39) 1.67 ± 0.08b (1.55–1.80)

0.020

***

0.054

*

0.008

***

0.023

NS

0.101

NS

0.053

NS

0.030

NS

0.024

*

a row, means without a common letter are significantly different (P < 0.05). in parentheses refer to ranges determined. *P < 0.05; **P < 0.01; ***P < 0.001. 1Values

Downloaded from http://ps.oxfordjournals.org/ at University of Guelph on November 20, 2014

< 0.05) AME compared with SBM from other origins. The average AME of SBM from the US, ARG, BRA, and IND were 2,375, 2,227, 2,317, and 2,000 kcal/kg, respectively.

AA differed (P < 0.05 to 0.0001) due to origin (Table 7). Among indispensable AA, differences were observed for Leu, Met, Phe, and Thr. The Leu, Met, and Thr contents were lowest (P < 0.05) in the IND samples and Met content was highest (P < 0.05) in the US samples. Among dispensable AA, as a semi-indispensable AA for poultry, Cys is of interest. Cysteine content of US samples was higher (P < 0.05) than those from ARG and IND, but similar (P > 0.05) to that from BRA. On a CP basis, differences (P < 0.05 to 0.001) existed across origins only for 3 indispensable AA (Met, Phe, and Thr; Table 8). Methionine contents were higher in the US samples compared with those in other SBM. Threonine and Phe contents were lower in the IND samples compared with those in other SBM. Cysteine contents were higher (P < 0.05) in the US samples compared with those in other SBM.

2573

EVALUATION OF SOYBEAN MEAL OF DIFFERENT ORIGINS Table 8. Total amino acid contents (% of CP, mean ± SD) of soybean meals from different origins1 Item Indispensable amino acid  Arginine  Histidine  Isoleucine  Leucine  Lysine  Methionine  Phenylalanine  Threonine

Dispensable amino acid  Alanine   Aspartic acid  Cysteine  Glycine   Glutamic acid  Proline  Serine  Tyrosine

Argentina (n = 16)

Brazil (n = 10)

India (n = 13)

7.53 ± 0.31 (7.15–8.21) 2.84 ± 0.10 (2.62–2.97) 4.70 ± 0.18 (4.38–5.12) 7.66 ± 0.21 (7.33–8.22) 6.10 ± 0.42 (5.50–6.79) 1.52 ± 0.05a (1.45–1.60) 5.15 ± 0.15b (4.93–5.55) 3.94 ± 0.09a (3.78–4.11) 5.22 ± 0.22 (4.90–5.69)

7.36 ± 0.30 (6.73–7.86) 2.79 ± 0.11 (2.59–2.99) 4.67 ± 0.21 (4.36–5.17) 7.53 ± 0.29 (6.98–8.29) 6.05 ± 0.43 (5.09–6.68) 1.45 ± 0.07b (1.30–1.55) 5.23 ± 0.25ab (4.86–5.62) 3.90 ± 0.17a (3.57–4.30) 5.14 ± 0.28 (4.64–5.80)

7.26 ± 0.18 (7.08–7.65) 2.79 ± 0.16 (2.47–3.08) 4.71 ± 0.24 (4.34–5.13) 7.74 ± 0.28 (7.35–8.22) 5.79 ± 0.53 (4.80–6.46) 1.44 ± 0.11b (1.24–1.65) 5.42 ± 0.30a (5.04–5.93) 3.85 ± 0.11ab (3.72–4.05) 5.09 ± 0.38 (4.50–5.67)

7.44 ± 0.28 (6.97–8.00) 2.85 ± 0.14 (2.60–3.15) 4.68 ± 0.27 (4.06–5.12) 7.48 ± 0.30 (6.82–7.82) 5.78 ± 0.46 (4.79–6.42) 1.41 ± 0.05b (1.33–1.49) 5.19 ± 0.20b (4.64–5.46) 3.77 ± 0.12b (3.55–3.96) 5.02 ± 0.34 (4.43–5.65)

4.10 ± 0.15bc (3.84–4.39) 11.57 ± 0.29 (11.07–12.30) 1.58 ± 0.07a (1.47–1.70) 4.03 ± 0.15 (3.76–4.30) 17.82 ± 0.76 (16.10–19.28) 5.19 ± 0.35 (4.47–5.72) 4.64 ± 0.18 (4.40–5.04) 3.67 ± 0.16 (3.43–4.10)

4.16 ± 0.16ab (3.90–4.56) 11.56 ± 0.54 (10.67–12.42) 1.52 ± 0.04b (1.42–1.58) 4.06 ± 0.19 (3.62–4.38) 17.78 ± 0.61 (16.81–19.33) 5.13 ± 0.41 (4.30–5.94) 4.62 ± 0.19 (4.11–4.83) 3.66 ± 0.21 (3.13–4.03)

4.25 ± 0.21a (3.93–4.67) 11.79 ± 0.58 (10.88–12.66) 1.52 ± 0.09b (1.43–1.73) 4.07 ± 0.16 (3.77–4.33) 17.90 ± 0.72 (16.97–19.13) 5.23 ± 0.31 (4.65–5.74) 4.64 ± 0.13 (4.40–4.88) 3.70 ± 0.22 (3.41–4.10)

4.02 ± 0.11c (3.75–4.23) 11.72 ± 0.54 (10.73–12.77) 1.45 ± 0.07c (1.34–1.58) 4.07 ± 0.24 (3.71–4.49) 18.19 ± 0.69 (16.40–19.14) 5.19 ± 0.31 (4.63–5.73) 4.65 ± 0.28 (4.25–5.10) 3.60 ± 0.16 (3.31–3.93)

Pooled SEM

P-value

0.078

NS

0.035

NS

0.063

NS

0.076

NS

0.127

NS

0.019

**

0.064

*

0.036

**

0.084

NS

0.044

*

0.136

NS

0.019

***

0.052

NS

0.193

NS

0.098

NS

0.057

NS

0.052

NS

a–cWithin

a row, means without a common letter are significantly different (P < 0.05). in parentheses refer to ranges determined. *P < 0.05; **P < 0.01; ***P < 0.001. 1Values

of all AA were influenced (P < 0.05 to < 0.001) by the origin of SBM. Trends for digestibility of AA generally followed that observed for CP, with IND samples having the lowest digestibility and no differences between samples from 3 other origins. Digestible contents of CP and all AA were influenced (P < 0.05 to 0.001) by the origin of SBM (Table 10). Digestible CP content was highest (P < 0.05) in the US samples and lowest (P < 0.05) in the IND samples. Digestible CP content of US SBM was higher (P < 0.05) than those of ARG and IND, but similar (P > 0.05) to that from BRA. The digestible CP content of SBM from the US, ARG, BRA, and IND was 40.0, 38.6, 39.8, and 36.7%, respectively. Digestible content of indispensable AA, in general, followed the same trend as that of digestible CP. The IND SBM samples had the lowest (P < 0.05) digestible AA content. No differences (P > 0.05) existed between the US and BRA SBM in the digestible contents of Arg, His, Ile, Leu, Met, and Phe. The digestible content of Arg, His, Leu, and Met in the US SBM was higher (P < 0.05) than those of ARG and BRA SBM. The digestible content of Lys, Thr, and Val in the US, ARG, and BRA samples was similar (P > 0.05). The digestible

Cys content in the US SBM was higher (P < 0.05) than that in SBM from other origins.

DISCUSSION Proximate Analysis and Carbohydrate Composition The proximate analysis and carbohydrate composition were within the range reported in the literature (Irish and Balnave, 1993; van Kempen et al., 2002, 2006; Grieshop et al., 2003; Thakur and Hurburgh, 2007; de Coca-Sinova et al., 2008; Frikha et al., 2012). But considerable variation was observed between SBM from different origins for these chemical components. The CP, fat, and fiber contents were higher and sucrose contents were lower in BRA samples compared with those from the US and ARG. The average CP content in the US, ARG, and BRA samples were 47.3, 46.9, and 48.2%, respectively. Higher CP content in BRA samples, compared with US samples, has been previously reported (Thakur and Hurburgh, 2007), which may be related to differences in agronomic factors and geographical location. The contributions of climate, espe-

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 Valine

United States (n = 16)

2574

Ravindran et al.

Table 9. Standardized ileal amino acid digestibility1 (%, mean ± SD) of the soybean meals from different origins2 Item CP Indispensable amino acid  Arginine  Histidine  Isoleucine  Leucine  Lysine  Methionine  Phenylalanine

 Valine Dispensable amino acid  Alanine   Aspartic acid  Cysteine  Glycine   Glutamic acid  Proline  Serine  Tyrosine

85 ± (82–87)

1.8a

90 ± (87–92) 86 ± (83–89) 85 ± (83–89) 85 ± (83–89) 88 ± (84–92) 88 ± (84–91) 86 ± (84–90) 81 ± (77–85) 84 ± (82–88)

1.3a

85 ± (83–88) 85 ± (82–89) 73 ± (64–80) 83 ± (78–88) 88 ± (86–91) 85 ± (82–89) 86 ± (81–89) 87 ± (85–90)

1.7a

2.1a 1.7a 1.6a 2.4a 1.7a 1.6a 2.2a 1.8a

1.7a 4.1a 3.3a 1.4a 1.9a 2.1a 1.5a

Argentina (n = 16) 82 ± (74–88)   88 ± (83–93) 84 ± (80–88) 84 ± (76–90) 84 ± (76–90) 86 ± (77–93) 86 ± (79–92) 85 ± (78–90) 79 ± (69–85) 83 ± (74–89)

4.1a

83 ± (75–89) 82 ± (75–88) 65 ± (48–77) 80 ± (67–88) 87 ± (80–92) 83 ± (75–87) 84 ± (76–88) 86 ± (79–91)

3.8a

3.0a 2.2b 3.8a 3.5a 4.5a 3.4a 3.5a 4.7a 4.0a

3.4b 8.9b 6.4a 3.1a 3.6b 3.8a 3.4a

Brazil (n = 10) 83 ± (75–87)   88 ± (83–92) 85 ± (79–89) 84 ± (76–88) 84 ± (77–88) 85 ± (76–93) 87 ± (80–92) 85 ± (78–88) 79 ± (71–84) 82 ± (75–87)   83 ± (76–87) 82 ± (77–86) 67 ± (55–77) 81 ± (70–86) 87 ± (81–90) 83 ± (77–86) 84 ± (77–88) 86 ± (80–90)

India (n = 13)

Pooled SEM

P-value

0.96

**

3.6a

79 ± (71–85)

3.8b

3.0a

86 ± (80–91) 81 ± (75–89) 80 ± (72–87) 81 ± (73–88) 82 ± (73–88) 84 ± (79–89) 82 ± (75–88) 75 ± (65–83) 79 ± (71–86)   80 ± (72–87) 79 ± (70–86) 58 ± (45–71) 75 ± (62–83) 84 ± (78–90) 79 ± (71–86) 79 ± (70–86) 82 ± (75–89)

3.7b

  0.78

4.0c

0.81

***

4.5b

0.99

**

4.2b

0.92

**

4.9b

1.20

*

3.0b

0.83

**

4.0b

0.88

**

5.2b

1.19

**

4.7b

1.04

**

4.5b

  0.99

4.6c

0.92

***

7.7c

1.96

***

6.2b

1.52

**

3.5b

0.79

**

4.2c

0.92

***

4.6b

1.00

***

4.2b

0.89

**

3.2ab 3.8a 3.5a 5.3ab 3.7a 3.4a 4.6a 4.0a 3.8a 3.2b 6.4ab 5.5a 3.0a 3.3ab 3.6a 3.4a

 

 

**

**

a–cWithin

a row, means without a common letter are significantly different (P < 0.05). digestibility values were standardized using the following basal ileal endogenous flow values (g/kg of DM intake): CP, 8.16; Arg, 0.37; His, 0.17; Ile, 0.34; Leu, 0.51; Lys, 0.29; Met, 0.10; Phe, 0.26; Thr, 0.60; Val, 0.45; Ala, 0.37; Asp, 0.59; Cys, 0.22; Gly, 0.62; Glu, 0.87; Pro, 0.33; Ser, 0.52; and Tyr, 0.28. 2Values in parentheses refer to ranges determined. *P < 0.05; **P < 0.01; ***P < 0.001. 1Apparent

cially temperature, and cultivar to geographic variability of CP content in soybeans have been demonstrated in a number of studies (Wolf et al., 1982; Breene et al., 1988; Piper and Boote, 1999). A noteworthy observation is that the CP content was more homogeneous among US samples compared with BRA samples. The CV was lowest for US samples and highest for BRA samples. The low variability in the US samples is probably reflective of uniform processing conditions and low genetic variability among current US soybean cultivars (van Kempen et al., 2002). Compared with SBM from other origins, those from IND had the lowest contents of CP, crude fat, and sucrose, and the highest contents of fiber, ash, and NSP. This finding was as expected because the IND samples are not dehulled and subjected to maximum possible extraction of oil during processing. The presence of hulls not only increases the fiber and NSP contents, but also serves as a diluent of nutrients (Dilger et al., 2004).

Sucrose content of US SBM was higher than that of other origins. This finding is of interest because it has been suggested that an increase in the sugar content results in the replacement of indigestible oligosaccharides and may improve the utilizable energy in SBM (de Coca-Sinova et al., 2008). A negative correlation (−0.33; P < 0.05) between sucrose and total NSP contents and a positive correlation (0.33; P < 0.05) between sucrose and AME contents observed in the current study (Table 11) lend support to this proposition.

Protein Quality Measurements A critical quality criterion in the selection of incoming SBM is to ensure that the samples are properly heat-processed because both undercooking and overcooking will lower the protein quality. Underheating, which may result in the incomplete destruction of antinutritional factors, is routinely verified by the urease

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 Threonine

United States (n = 16)

2575

EVALUATION OF SOYBEAN MEAL OF DIFFERENT ORIGINS

Table 10. Standardized digestible amino acid content (%, mean ± SD) of soybean meals from different origins, as-received basis1 United States (n = 16)

Item

0.82a

CP Indispensable amino acid  Arginine  Histidine  Isoleucine  Leucine  Lysine  Methionine  Phenylalanine

 Valine Dispensable amino acid  Alanine   Aspartic acid  Cysteine  Glycine   Glutamic acid  Proline  Serine  Tyrosine

3.19 ± 0.12a (3.03–3.48) 1.16 ± 0.05a (1.06–1.23) 1.89 ± 0.07a (1.74–2.03) 3.09 ± 0.10a (2.89–3.28) 2.52 ± 0.22a (2.21–2.92) 0.63 ± 0.02a (0.58–0.68) 2.10 ± 0.07ab (1.96–2.24) 1.51 ± 0.05a (1.45–1.61) 2.07 ± 0.09a (1.88–2.22) 1.64 ± 0.06ab (1.53–1.73) 4.67 ± 0.14a (4.42–5.02) 0.54 ± 0.05a (0.45–0.63) 1.59 ± 0.10a (1.42–1.73) 7.43 ± 0.26a (6.85–8.00) 2.09 ± 0.11a (1.84–2.26) 1.88 ± 0.10a (1.77–2.07) 1.51 ± 0.08a (1.41–1.72)

1.96b

38.6 ± (34.2–41.2)   3.05 ± 0.16b (2.80–3.33) 1.10 ± 0.06bc (0.98–1.19) 1.83 ± 0.09ab (1.65–1.95) 2.96 ± 0.12b (2.67–3.15) 2.44 ± 0.23a (1.88–2.69) 0.59 ± 0.04b (0.54–0.65) 2.08 ± 0.13b (1.83–2.28) 1.45 ± 0.11a (1.23–1.59) 1.99 ± 0.10a (1.80–2.15)   1.62 ± 0.08b (1.43–1.72) 4.45 ± 0.26b (3.91–4.84) 0.46 ± 0.07b (0.34–0.54) 1.53 ± 0.17ab (1.19–1.72) 7.21 ± 0.29ab (6.53–7.57) 1.99 ± 0.15ab (1.66–2.22) 1.82 ± 0.13ab (1.54–2.00) 1.48 ± 0.12a (1.27–1.65)

Brazil (n = 10) 1.99ab

39.8 ± (36.5–42.7)

3.09 ± 0.14ab (2.87–3.41) 1.14 ± 0.09ab (1.00–1.32) 1.89 ± 0.12a (1.75–2.19) 3.12 ± 0.17a (2.88–3.52) 2.39 ± 0.33ab (1.75–2.83) 0.60 ± 0.06ab (0.52–0.73) 2.21 ± 0.16a (1.94–2.45) 1.47 ± 0.10a (1.31–1.65) 2.02 ± 0.17a (1.80–2.38) 1.70 ± 0.10a (1.53–1.87) 4.67 ± 0.28a (4.21–5.07) 0.49 ± 0.06b (0.41–0.59) 1.58 ± 0.12a (1.32–1.72) 7.48 ± 0.42a (7.00–8.40) 2.10 ± 0.16a (1.84–2.39) 1.87 ± 0.13a (1.63–2.14) 1.53 ± 0.12a (1.32–1.69)

India (n = 13) 2.05c

36.7 ± (32.5–40.5)   2.96 ± 0.17b (2.69–3.22) 1.08 ± 0.08c (0.95–1.20) 1.75 ± 0.16b (1.44–1.97) 2.80 ± 0.21c (2.44–3.25) 2.21 ± 0.28b (1.71–2.55) 0.55 ± 0.02c (0.51–0.60) 1.97 ± 0.15c (1.69–2.23) 1.31 ± 0.11b (1.14–1.53) 1.84 ± 0.17b (1.56–2.17)   1.49 ± 0.11c (1.31–1.71) 4.30 ± 0.37b (3.77–4.85) 0.39 ± 0.06c (0.29–0.51) 1.43 ± 0.17b (1.12–1.61) 7.10 ± 0.48b (6.17–7.86) 1.91 ± 0.18b (1.64–2.23) 1.72 ± 0.17b (1.46–1.95) 1.37 ± 0.11b (1.21–1.55)

Pooled SEM

P-value

0.49

***

  0.042

 

**

0.019

*

0.031

**

0.042

***

0.072

*

0.010

***

0.036

**

0.027

***

0.036

***

  0.024

 

***

0.074

**

0.016

***

0.040

*

0.102

*

0.042

*

0.037

*

0.030

**

a–cWithin

a row, means without a common letter are significantly different (P < 0.05). in parentheses refer to ranges determined. *P < 0.05; **P < 0.01; ***P < 0.001. 1Values

activity index test. Overheating causes Maillard reactions, which decrease the availability of heat-sensitive AA and are assessed by the KOH protein solubility test. Although published data on commercially acceptable values for these in vitro quality measurements are inconsistent, the general recommendation is that adequately heat-processed SBM should have a urease index of 0.10 pH unit change or below and KOH solubil-

Table 11. Correlation coefficients of the AME of soybean meal with selected measurements of interest Item KOH protein solubility CP Crude fat Crude fiber Ash NDF Sucrose Insoluble NSP Total NSP 1NSP

= nonstarch polysaccharide.

r

P≤

0.01 0.18 0.38 −0.64 −0.63 −0.69 0.33 −0.63 −0.68

0.98 0.20 0.01 0.0001 0.0001 0.0001 0.05 0.0001 0.0001

ity between 78 and 85% (Van Eys, 2012). Though there were differences in the urease index of SBM from different origins, the differences were of small magnitude and all the values were within normal limits, suggesting that none of the samples were undercooked. Across the origins, KOH protein solubility of some samples was determined to be below the 78% threshold, indicating some degree of overprocessing. The average solubility values for SBM of all origins, however, were within the acceptable range. In the samples evaluated, there was a lack of correlation between KOH protein solubility and in vivo protein digestibility (Table 12), which was unexpected and contrary to published data (Parsons et al., 1991). On the other hand, this finding is not surprising because the current samples, irrespective of the origin, would have been subjected to standardized processing conditions (in terms of temperature and duration of heat treatment), whereas studies that demonstrate the usefulness of KOH protein solubility as protein quality tests have used extreme processing conditions to establish the correlations (Parsons et al., 1991).

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 Threonine

40.0 ± (38.8–41.3)

Argentina (n = 16)

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Ravindran et al.

Table 12. Correlation coefficients of in vivo protein digestibility of soybean meal with selected measurements of interest Item KOH protein solubility Urease index Trypsin inhibitor activity Crude protein Crude fiber Crude fat Ash NDF1 Sucrose Insoluble NSP1 Total NSP 1NDF

r

P≤

−0.01 0.24 0.27 0.08 −0.56 0.33 −0.55 −0.67 0.41 −0.55 −0.57

0.99 0.08 0.051 0.60 0.0001 0.05 0.0001 0.0001 0.01 0.0001 0.0001

= neutral detergent fiber; NSP = nonstarch polysaccharide.

Minerals No previous study has investigated the variation in mineral profile between SBM origins. The present findings showed that there were marked differences due to origin for all minerals. Of particular note is the relatively high content of Ca in the US and IND SBM compared with that from ARG and BRA. In the US, limestone is often added, up to a maximum of 0.5%, as a flow agent to SBM at the end of processing to prevent caking of the warm meal (Edwards, 1993), and this may explain the high Ca in the US samples. Among the microminerals, Fe content was 8- to 9-fold higher in SBM from IND origin than those from other origins. Such high value for Fe is an anomaly and possibly indicates contamination with soil, contamination during processing, or both. These iron levels, however, should not cause any practical problems because the maximum tolerance level of Fe in poultry diets is reported to be 500 mg/kg (NRC, 2005).

AME Due to the lack of starch (Wilson et al., 1978) and a high content of NSP belonging to the indigestible dietary fiber fraction, the AME of SBM is low for broiler chickens. The present data demonstrated that the AME of SBM from different origins varied widely, rang-

Contents and Digestibility of AA The determined total AA contents of SBM samples were within the range reported in the literature (van Kempen et al., 2002, 2006; Thakur and Hurburgh, 2007; de Coca-Sinova et al., 2008; Evonik, 2010; Frikha et al., 2012; Goerke et al., 2012; NRC, 2012). Despite significant differences in the CP content of SBM from different origins, only 8 of the 17 AA differed due to origin. Among indispensable AA, differences were observed for Leu, Met, Phe, and Thr. Leucine, Met, and Thr contents were lowest in the IND samples. The sulfur-containing AA, Met and Cys, are the first limiting AA in corn-based poultry diets, and the contents of these 2 AA, both on an as-received basis and a CP basis, were highest in the US samples. Cysteine, because of the presence of disulfide bonds, is the most heat labile of all AA (Wall, 1971), and its susceptibility to heat has long been known (Evans and McGinnis, 1948). High contents of Cys in the US samples suggest that processing conditions may be optimal in US plants. In general, the ileal AA digestibility data for SBM determined for broilers in the current work agree with published data (Ravindran et al., 2005; de Coca-Sinova et al., 2008; Frikha et al., 2012). Ileal digestibility of CP and AA was higher in SBM from the US, ARG, and BRA compared with those from IND. No differences in digestibility were observed across US, ARG, and BRA samples. Soybean meal is priced by purchasers primarily on the basis of CP content. While this simplistic approach may be useful to adjust the matrix values for total AA, it is not valid when comparing meals of different contents of fiber, carbohydrate, fat and ash, which are known to influence the availability of CP and energy. Perhaps the interesting finding of the current work is the lack of correlation between CP content and nutritive quality of SBM. Data shown in Tables 11 and 12 show that the CP content of SBM was not correlated with either ileal CP digestibility (r = 0.08; P > 0.05) or AME (r = 0.18; P > 0.05) and is not indicative of AA

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The activity of TI in SBM differed across origins, but the determined values (2.0–2.5 TIU/mg) were lower than the TI tolerance level reported for broilers. Loeffler et al. (2012) found that young broilers seem to tolerate TI levels up to 4.1 TIU/mg in the diet and perform normally. Urease test is an indirect test of TI activity, based on the assumption that the heat denatures TI and urease to a similar extent. In the present study, the urease index and TI units were highly correlated (r = 0.63; P < 0.0001), confirming the validity of this assumption. Urease index tended (r = 0.24; P = 0.08) to be positively correlated with in vivo protein digestibility. This observation was counterintuitive and clearly an anomaly because urease values for samples were within an acceptable range.

ing from 1,567 to 2,541 kcal/kg. On average, SBM from the US had an advantage of 148, 58, and 375 kcal/kg, respectively, over ARG, BRA, and IND samples. This comparison highlights the potential economic benefit of SBM from the US, even when priced higher than the other SBM sources. These AME differences between US and ARG, BRA, and IND origins will be worth US $46,250, 18,125, and 117,188 per year in a feed mill producing 10,000 t of feed per year. This calculation assumed that the feed on average contains 25% SBM and feed grade fat is valued at US $1,000 per t and contains 8,000 kcal/kg of AME. Correlation analyses (Table 11) showed that the AME was positively influenced by crude fat (r = 0.38; P < 0.01) and sucrose (r = 0.33; P < 0.05), and negatively influenced by crude fiber (r = −0.64; P < 0.0001) and ash (r = −0.63; P < 0.0001).

EVALUATION OF SOYBEAN MEAL OF DIFFERENT ORIGINS

REFERENCES AOAC International. 2005. Official Methods of Analysis. 18th ed. AOAC Int., Gaithersburg, MD. Araba, M., and N. M. Dale. 1990. Evaluation of protein solubility as an indicator of overprocessing soybean meals. Poult. Sci. 69:76–83. Association of Official Analytical Chemists. 1980. Official Methods of Analysis. 12th ed. Association of Official Analytical Chemists, Washington, DC. Breene, W. M., S. Lin, L. Hardman, and J. Orf. 1988. Protein and oil content of soybeans from different geographic locations. J. Am. Oil Chem. Soc. 65:1927–1931. de Coca-Sinova, A., D. G. Valencia, E. Jimenez-Moreno, R. Lazaro, and G. G. Mateos. 2008. Apparent ileal digestibility of energy, nitrogen and amino acids of soybean meals of different origin in broilers. Poult. Sci. 87:2613–2623. Dilger, R. N., J. S. Sands, D. Ragland, and O. Adeola. 2004. Digestibility of nitrogen and amino acids in soybean meal with added soyhulls. J. Anim. Sci. 82:715–724. Edwards, H. M. Jr. 1993. Dietary 1,25-Dihydroxycholecalciferol supplementation increases natural phytate phosphorus utilisation in chickens. J. Nutr. 123:567–577. Englyst, H. N., M. E. Quigley, and G. J. Hudson. 1994. Determination of dietary fibre as non-starch polysaccharides with gas-liquid chromatographic, high-performance chromatographic or spectrophotometric measurement of constituent sugars. Analyst (Lond.) 119:1497–1509. Evans, R. J., and J. McGinnis. 1948. Cystine and methionine metabolism by chicks receiving raw or autoclaved soybean oil meal. J. Nutr. 35:477–488. Evonik. 2010. AMINODat 4.0. Evonik Industries, Evonik Degussa GmbH, Hanau-Wolfgang, Germany.

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or energy available for utilization by the animal. These data highlight the weakness of selecting and pricing SBM based on CP content. It is generally assumed by the feed industry that the digestible AA content of SBM per unit of CP is constant and the variability due to origin is not considered. The present data on digestible contents of CP and AA showed that these parameters were influenced by the origin of SBM. Digestible CP content of US SBM was higher than those of ARG and IND, but similar to that from BRA. Digestible contents of indispensable AA, in general, followed the same trend as that of digestible CP. But the digestible Cys content in the US SBM was higher than that in SBM from other origins. Over the years, a large volume of information has become available on the nutrient composition (CP, fat, crude fiber, and total AA) of SBM and these data have been used by the feed industry to develop nutrient matrices for feed formulations. However, very little information is available on the variability that exists in AME and digestible AA. The present data demonstrated that differences exist in the nutrient contents of SBM from different origins. This evaluation additionally demonstrated that there were also differences in the digestible contents of CP and AA and AME across origins and provides baseline data for the variation that could be expected for SBM originating from these 4 major producers.

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